Sequencing mechanism for a fuel control

ABSTRACT

BY A SEQUENCING CONTROL, FUEL IS SEQUENTIALLY FED TO A PLURALITY OF NOZZLES DISPOSED AT DIFFERENT STATIONS IN AN ENGINE. THE SEQUENTIAL CONTROL INTERCONNECTS THE NOZZLES WITH METERED FUEL FROM A MAIN FUEL CONTROL IN A PREDETERMINED MANNER IN RESPONSE TO POWER LEVER POSITION ONCE THE NOZZLES ARE FILLED FROM ANOTHER SOURCE OF FUEL.

United States Patent [72] Inventors George A. Fisher Appl. No. FiledPatented Assignee CONTROL 5 Claims, 3 Drawing Figs.

Int. Cl. F02; l/06 Field of Search 60/3928,

Saugus, CellL;

Charles F. Stearns, East LOIIIIIIQIIIOW, Mus.

June 26, 1969 June 28, 1971 United Aircraft Corporation East Hartford,Conn.

seousucmc MECHANISM FOR A FUEL n 13,ss1,231

References Cited UNITED STATES PATENTS 5/1950 Redding 60/261X 1]] 956Crim 60/ 39.74U'X 2/1957 Karen 60/39.74X 2/1966 Rogers et al.'. 60/2372/ 1966 Andrews 60/241X 1119.68 Rimmer 60/237 Primary Examiner-AlLawrence Smith Attorney-Norman Friedland ABSTRACT: By a sequencingcontrol, fuel is sequentially fed to a plurality of nozzles disposed atdifferent stations in an engine. The sequential control interconnectsthe nozzles with metered fuel from a main fuel control in apredetermined v manner in response to power lever position once thenozzles are filled from another source of fuel.

PATENT EU uues um SHEET 1 UF 2 M? 1 Jill? INV ENTORS GEORGE A. FISHERCHAR? FSTEARNS BY M)! ATTORNEY P= PRESSURE PATENTEUJuuza l9?! SHEET 2[IF 2 FIG. 3

SEQUENCING MECHANISM FOR A FUEL CONTROL CROSS-REFERENCES TO RELATEDAPPLICATIONS This invention is related to US. application entitledSequential Fuel Control" Ser. No. 836,827 filed June 26, I969, by D. E.Anshutz and K. L. Linebrink and assigned to the same assignee.

BACKGROUND OF THE INVENTION This invention relates to fuel controls andparticularly to sequencing mechanism serving to connect the metered fuelto a plurality of nozzles in a predetermined manner.

As is well known in certain types of jet engines it is customary tomount a plurality of nozzles at various locations in the combustionsection to optimize combustion efficiency and it is desirable tosequentially feed these nozzles with fuel in a predetermined patternsuch that certain segments of nozzles are fed with fuel prior to feedingthe other segments. Thus, the purpose of the control is to provideproper sequencing of fuel fiow to the nozzles filling said nozzles priorto distributingthe proper metered fuel flow thereto.

SUMMARY OF INVENTION A primary object of this invention is to provide asegment sequence control for delivering fuel to combustion sections of aturbine type of power plant. It is to be understood that what is meantby combustion section is any station where combustion occurs; thisincludes within the ducts of bypass types of engines, afterbumers andthe like.

A still further object of this invention is to provide in a sequentialcontrol means for filling the nozzles and their connecting line withfuel from a source of fuel prior to delivering metered fuel to saidnozzles.

A still further object of this invention is to provide in a sequentialcontrol means for coordinating the filling with fuel a plurality ofburner segments in a predetermined sequence in response to a remotelymounted power lever of an aircraft with the ability to select the numberof segments desired and to provide for the cutting off of fuel in apredetermined manner.

Other features and advantages will be apparent from the specificationand claims and from the accompanying drawings which illustrate anembodiment of the invention BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 isa schematic illustration, partly in sectional, showing the details ofthis invention.

FIG. 2 is a schematic illustration showing the sequence controldistributor valve connected to the segments in the burner section of abypass of a jet engine partially shown.

FIG. 3 is another schematic illustration showing another embodiment ofthis invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 'many lines as there are nozzlesegments and the number of pipes and nozzle segments not being limitedbut depending rather from the design criteria of the particular engine.Distributor valve to comprises a rotary valve element l9 having acentral bore 2! formed therein communicating with a radial passage 32adapted to selectively register with a plurality of circumferentiallyspaced ports 3 36, 38, d0, 42, and M. In addition, an arcuate slot isformed therein having sufficient area to span the entire arc of portsincluding 34 through 44, inclusively. Thus, rotation of valve elementwill first place radial passage 32 in line with 34 for receiving fuelfrom a separate source to be described hereinbelow prior tocommunicating with passage 50 defined by the arcuate slot 52 formed inthe rotary valve element. Rotation of the valve element to the next port36 places in communication the port 34 and the annular space 50 to whichis fed metered fuel as will be described hereinbelow.

Therefore, from the foregoing, it is apparent that selectivelypositioning the radial passage 32 to register with radial passages 34through 44 inclusively will first place fuel from a separate source tofill the lines communicating with the respective ports prior to placingthe metered fuel evidenced in the chamber defined by the arcuate slot 52for delivering metered fuel to the respective segments of the enginesscombustion chamber. As noted from FIG. 1, metered fuel is admitted tothe distributing valve through drilled passage 60 and into chamber 50for selectively being admitted to the various flow lines interconnectingports 34 through 44 inclusively and the burner segments.

The fill flow which is fuel pressurized by the fuel pumping system isadmitted to fill fiow shutoff valve 70 via line 72, valve 70 serving toassure that the fuel is not admitted into the system until actuated bythe latching mechanism generally indicated by reference numeral 144consisting of valves 142 and M3. As noted from FIG. I valve element 74moves against the compression spring 76 and the pressure in chamber 71delivering fuel to the fill flow throttle valve generally indicated bynumeral 78 via line 80 and pressure regulator generally indicated bynumeral 82. The shutoff valve will be described in more detailhereinbelow. The pressure regulator serves to maintain the pressure dropacross the metering orifice 84 at a constant value, which is dictated bythe force of spring 86. The valve operates by sensing upstream anddownstream pressure across metering orifice 84 by admitting upstreampressure to act on one face of valve element 88 and downstream pressureto act on the opposing face of element 88, pressure being admittedthereto respectively via passages 90 and 92. Since the area is equal,the force created by spring 86 acting in concert with downstreampressure urges valve element 88 to open valve metering element 93 withrespect to the valve seat 94. This force is counteracted by the forceacting on the underside of valve element 88. When the total force of thepressure on the upperside of valve element 88 and spring 86counterbalance the force acting on the underside, the pressure drop (AP) across metering orifice 84 will be equal to the force of spring 86.Any deviation from the balance will adjust valve element 88 until the AP is returned to its selected value.

Fuel admitted into orifice 84 passes through an axial drilled passage 96formed in the fill flow throttle valve 98 and communicates with radialpassage 32 formed in the rotating distributing valve element 19.

From the foregoing it is apparent that the rotary distributor valveelement 19 serves to fill the one line interconnecting the burnersegment with fuel delivered from one source and then proceeds to fillthe next adjacent segment, which fuel being metered from the main fuelcontrol, shown in blank, enters the fuel section to deliver metered fuelto that particular connecting segment ring just filled. By contouringorifice 84 as shown, it is possible to select the rate at which eachsegment will fill. It is understood, as is obvious to one skilled in theart, that the outer window (orifice) cooperating with the inner windowhas a fixed metering area and the total metering area will be dictatedby the portion of the windows that is exposed to the fuel flow.

The next portion of the description will describe the actuation of therotary distributor valve I9. As noted from FIG. I, the fill flowthrottle valve 98 is connected to the rotary distributor valve I) by anaxial hollow shaft I00. Shaft I00 carries pinion gear I02 which is inmuting relation to the rack gear I04, the details of both beingeliminated for the sake of convenience as any means of actuation willfall within the purview of this invention. The rack gear 104 is madeintegral with the connecting shaft 106 interconnecting the pistons 108and IE0. Fluid admitted to these pistons serves to position them with aconsequential movement of the rack 104 and a likewise rotary movement ofthe distributor valve 19. This movement is made in response to the powerlever generally indicated by numeral 112 which serves to control thepower lever servo 136 and the cooperating cam 172 which, in turn,schedule the segments in a predetermined manner but assuring that thefill is manifested before the various burner segments are connected tothe metered fuel. Power lever adapted to be positioned for admittingfuel to the segments is connected to cam 114 via the schematicallyillustrated connection 116. Cam 172 is adapted to schedule one or all ofthe segments in sequential order and by moving it to the extent of itstravel which will be the high point of the node, follower 118 is forcedupwardly causing the pilot valve 120 to move in an upward position. Aswould be obvious to one skilled in the art, cam 172 can be used toadjust the fuel control so as to properly schedule metered fuel flowwith the actuated segments. The lands on valve 120 uncover ports 122,124 and 126 for communicating high pressure line 128 with line 130 foradmitting pressurized fluid into chamber 132 of piston actuator 134.However, piston 136 will remain stationary until fluid present inchamber 138 formed on the back side of piston 136 is drained. Drainingof this chamber is effectuated by latching mechanism 144. As can be seenfrom the drawing, latching mechanism 144 is connected to the lever 146and serves to open chamber 138 to drain by positioning valve element 142downwardly. Hence, piston 136 will remain stationary notwithstanding theadmittance of pressurized fluid in chamber 132 until line 152 isconnected to drain via line 140, pilot valve 120, and drain connection139.

The latching mechanism 144 is controlled by fill sensor generallyindicated by numeral 156. The fill sensor measures the fluid beingadmitted to the various fill lines and responds to the fluid in the linecommunicating with the source of fill fluid. While the particular meansfor sensing when a segment line is filled does not form a limitation tothe invention, in this instance the fill sensor measures the pressuredrop across orifice 84 and when that approaches zero, the flapper valve158 will shut off the flow from orifice 160 to build up the pressuredownstream of restrictor 162 which ultimately is admitted into actuator164 via connecting line 166. Thus, when the pressure drop across orifice84 is at zero, pressure is admitted behind piston 168 urging it againstspring 171 in a downward direction for positioning lever 146 downwardlyand with a like movement of valve element 142 being connected thereto bythe pin connection 170. This movement interconnects line 152 with line140 for draining chamber 148. Piston 136 is then urged upwardly and byvirtue of the rack and pinion connection generally indicated by numeral173 causes the power lever servo cam 172 to rotate and position valveelement 174 upwardly. Lever 146 abuts against the projecting pin 176 andsince it is moved upwardly likewise lever 146 also moves upwardlyrepositioning valve element 142 to the closed position and hencelatching the system until the next segment is filled.

As noted, the fill sensor 156 consists of piston 180 having one surfaceexposed to pressure upstream of orifice via line 182 and the othersurface to pressure downstream of orifice 84 via line 184. Hence, thepressure acting across orifice 84 and the force of spring 181 is felt bypiston 180 and moves flapper 154 relative to orifice 160 by virtue ofthe connecting rod 188. High pressure discharging from 160 is normallydumped to drain (i.e. pump inlet) via port 190 so that closure offlapper valve 158 builds up pressure downstream of orifice 162 disposedin line 192 which in turn is transmitted to chamber 164 via line 166 andthe Most selector valve 194.

Thus, from the foregoing, it is apparent that the admittance of pressureinto chamber 132 and the dumping of pressure from chamber 148 permitspiston 136 to move axially for rotating cam 172. The cam motion ispicked up by follower 200 suitably attached to the lever 202 which isalso pinned to the pilot valve 120 by pin 204. This feeds back thesignal to the pilot valve to return it to its null position such thatthe lands 122, 124, 126 are in line-on-line with the respective portswhich will occur only when the signal scheduled by the pilot lever 112as seen on cam 114 is matched by the number of segments actuated. Thusif the power lever is positioned to fill the six segments, then the nullposition will be reached solely when the six segments are filled.

in addition, the motion of cam 172 is also picked up by follower 208which is suitably connected to fulcrumed lever 210 having one endbearing against spring 212 disposed on the top surface of pilot valve214. Pilot valve 214 serves to position pistons 108 and 110 forcontrolling movement of the segment distributor valve 19. This iseffectuated by applying a pressure signal to chamber 216 via drilledpassage 218 and line 220. This is accomplished by controlling thepressure drop across fixed restriction 222 disposed in line 220 which isin communication with regulated pressure discharging from the pressureregulator indicated in blank by reference numeral 224 which is fed bypump 226 in communication with reservoir 228. As noted from FIG. 1, thebranch line 230 downstream of fixed restriction 222 feeds into chamber232 which has disposed therein bellows 234. Formed on the free end ofthe bellows and centrally disposed thereof is orifice 236 which is inproximity to the projection 238. Movement of the bellows 234 positionsorifice 236 relative to projection 238 for effectuating closure thereof.The bellows is controlled by the push rod 240 which is urged against cam242 attached to the hollow shaft 100. Rotation of the hollow shaftrotates cam 242 to position push rod 240 relative thereto and for eachposition of cam 242 there will be a corresponding position of orifice236 and likewise there will be a corresponding pressure in chamber 216for positioning the land of spool 214 relative to the various ports.Thus, high pressure admitted into port 250 is either directed to line252 or 254 depending whether the spool has been moved upwardly ordownwardly. lf 252 is connected to high pressure, then 254 is connectedto drain via line 256. Conversely, if high pressure is admitted to 254,then line 252 is connected to drain via line 258. Lines 252 and 254 arein communication with the ends of pistons and 108 respectively, foreffectuating movement thereof. The force of the pressure acting on theend of spool 214 created by the pressure in chamber 216 is counteractedby the force produced by spring 212. When these forces are balanced, nomovement of pistons 108, 110 will occur. Accordingly, for each positionof rotary distribution valve 19 there will be a corresponding positionof cam 242 and a likewise corresponding position of lever 210 and pilotvalve 214 will be at the null position.

To effectuate closure of the various segments, the pilot lever isreturned to its original position rotating cam 114 to the lower pointimparting an unbalance to lever 202 with a consequential downwardmovement of pilot valve 120. This positions lands 122, 124, and 126downwardly to uncover the various communicating ports for applying highpressure from line 128 to the Most selector valve 194 via line 260. Thismoves the ball 262 downwardly to block off flow from line 192. Piston168 moves downwardly for disanning the latching mechanism 136 by aconsequential downward positioning of valve element 142. High pressureis then applied from line 266 into line 140 by land 126 for applyinghigh pressure into chamber 138 via the latching valve 144 and line 152urging piston 136 downwardly for rotating the power lever servo cam 172by the rack and pinion mechanism generally indicated by numeral 173.Pilot valve is continuously urged in a downward direction by action ofspring 272. Obviously, rotation of cam 172 in a downward direction willcause an unbalance on spring 212 by the movement of lever 210. As theload decreases by rotating lever 210 counterclockwise, the pilot valvewill move so that the lands are positioned to communicate the pressurebehind piston 110 and the pressure behind piston 108 so that it willmove in a decreasing direction. It will continue to move until thescheduled signal imposed by cam 114 is satisfied. Any number of nozzlescan be shut off in a descending manner. Thus, movement of power lever ifadvanced, initiates the various segments sequentially in an ascendingorder and if retracted, turns off any given number of segments in adescending order.

OPERATION OF THE SEQUENCE SEGMENT CONTROL Assume the pilot is callingfor the full number of segments to be turned on, he will advance thepilot lever to the full open position. This, in turn, rotates cam 114 tothe high point creating an unbalance on fulcrum lever 202 forpositioning the pilot valve 120. This, in turn, admits high pressureservo fluid into the pilot lever servo piston 136 for urging itupwardly. Since chamber 148 is filled with fluid, the piston will notmove until this fluid is dumped. Dumping of fluid from chamber 148 iseffectuated by actuating the latching mechanism 144 by unseating valve142 in response to the fill sensor 156 sensing fill line 96 by measuringthe pressure drop across orifice 84. When the line is filled, i.e., whenthe A P across 84 is substantially zero, and this will occur since thepressure drop is being felt across the nozzles when the line is filled,this signal is transmitted to latching servo 164 by closing off theflapper orifice 160 with flapper element 158. As noted from FIG. I, thepressure drop is measured across the fill flow shutoff valve 74 and inline pressure regulator 82 inasmuch as this is an indication of the A Pacross orifice 84. As would be obvious to one skilled in the art, anyother pressure indicative of A P across orifice 84 can be utilized.This, in turn, allows the pressure in line 192 to increase and thispressure is in turn felt on the back side of piston 168 being incommunication with line 166 which is in communication with line 192.Piston 168 moves down forcing lever 146 to pivot clockwise about pin I76therefore carrying valve 142 downwardly to open up line 140 to line 152.Since land 126 has moved upwaRdly, drain line 139 communicates with line140 for draining the fluid in chamber 148, and permitting the piston 136to move upwardly for rotating cam 172 allowing lever 146 which isbalanced by spring 280 to move to its latching position. The meteringland of valve 284 serves to assure that the shutoff valve 74 is closedwhen the filling process is completed. Hence, once the line is filledwith fuel from a separate source, say directly from the pumps, thedistributor valve 19 is allowed to rotate so as to place metered fuelfrom the main fuel control in communication with the segment justfilled. The rotation of the metering valve then places the radialpassage 32 of distributor valve 19 in communication with the next line36. Line 36 fills up in a similar manner and when it is completelyfilled, the pressure drop across 84 again becomes zero reactivating thelatching mechanism 136 to allow the distributor valve to move in themanner just described above. Of course, the movement of the distributorvalve is dictated by the position of cam 172 which controls the pilotvalve 214 for applying and draining pressure from pistons I08 and 110respectively, depending on whether the nozzles are filling or emptying.

Another embodiment of this invention is illustrated in FIG. 3 whereinthe segment sequence control sequentially and automatically fills andcommunicates the nozzles and interconnecting passages with metered fuelin successive order until all of the burner segments are operative. Asnoted, the distributor valve generally indicated by numeral 300comprises piston 302 disposed in one end of cavity chamber 304 anddefining therewith chamber 306. Piston 302 carries an elongated hollowmember 308 concentrically mounted to and extending beyond elongatedtubular member 310 depending flange 312 defining an end cap and valveelement is formed adjacent opening 314. When the sequential control isinoperative, fuel is recirculated from the pump and flows from inlet 316through opening 314, the center passage 320, space 318, and passage line319 which is, in turn, connected with the fuel pumping system, notshown. Upon actuation of piston 302 by draining fluid from chamber 306,piston 306 moves leftwardly so that valve element 312 seats against theend of member 310 blocking off the flow through center passage 320.

Movement of piston 302 leftwardly also moves the flange element 324fonned on the end of member 308 which serves to interconnect line 319with port 332 formed in the axial member 310 and places annular passage334 into communication therewith for leading fuel from the pump tosegment line 336 through opening 338. Further movement of piston 302leftwardly positions opening 338 with the next adjacent nozzle line 340.This movement also moves the end flange 312 and valve element leftwardlyto uncover line 336 exposing it to metered fuel evidenced in line 3l6whi'ch, in turn, is delivered to the burner segments similarly totha't'described in the above with reference to FIG. 1. Uponfillingnozzle 340, piston 306 moves to the next nozzle interconnectingit with fill pressure and communicating 340 with metered fuel. Piston302 will continue its travel until all the nozzles are filled andcommunicated with metered fuel.

Control of distributor valve 300 is effectuated by the segment flowcontrol valve generally illustrated by numeral 350 and the segment flowcontrol valve generally indicated by numeral 352. The system is actuatedby positioning pilot lever 354 which, in turn, rotates cam 356. Cam 356actuates valve 358 for applying servo pressure into the end of segmentcontrol valve 350 via line 360. Segment control valve comprises aplurality of segmental pistons cooperating to push on push rod 364.Thus, applying pressure into chamber 366 urges segment 368 leftwardlybecause it abuts against the next segment 370 which in turn transmits asignal to push rod 364 which is rotary pinned to lever 380 by pin 400.Leftward movement of push rod 364 causes lever 380 to rotatecounterclockwise about pivot 382 and consequently positions spool 384which is pinned thereto by pin 386. Movement of spool 384 positions land388 uncovering drain port 390 which drains chamber 306 via line 392.This moves valve element 324 to uncover port 332 for communicating pumppressure directly with the segment 336 via the opening 332, annularpassage 334 and opening 338. As piston 302 moves to the positiondescribed in the preceding sentence, the piston feeds a signal back topull valve 352 by lever 380.

As described above, when nozzle 336 is filled, the pressure in the lineis sensed by pressure tap 396. This, in turn, is transmitted to asegmental piston of segment control vaLve 350. Each segmental piston hasa similar pressure tap connection, serving to sense fuel pressure in theburner nozzles. The application of sensed fuel pressure adjacentsegmental piston 370 into segment control valve positions it leftwardlyto move push rod 364 to the left for repositioning segment flow controlvalve 352 to uncover port 390 for further draining chamber 306 as wasdescribed above. Nozzle 336 will now be directly connected to meteredfuel (from the main fuel control) evidence in line 316 andsimultaneously interconnecting the next segment 340 with opening 338 forfilling from the pump. This continues until all of the segments areplaced in communication with the metered flow subsequent to beingfilled.

As noted, when piston 302 moves leftwardly, it pivots about connectingpin 400 urging the spool 384 of the segment flow control valve 352 tothe right for returning the spool back to its line-on-line position.Thus, the segment flow control valve is always returned to its nullposition upon movement of the piston 302 to the desired location,assuring-that the nozzles are not connected to pump pressure until theprevious nozzle has filled as sensed by the individual pressure taps.

It should be understood that the invention is not limited to theparticular embodiments shown and described herein, but that variouschanges and modifications may be made without departing from the spiritor scope of this novel concept as defined by the following claims.

We claim:

1. A fuel control for a turbine type of power plant having a burnersection including a plurality of burner segments disposed along variousstations thereof, a power lever, means for delivering metered fuel tosaid various burner segments and means for filling said burner segmentswith fuel other than the metered fuel, sequential control meansresponsive to said power lever and the pressure in said burner segmentsfor controlling said filling means for filling each of said burnersegments in a successive predetermined pattern and for controlling saiddelivery means for delivering fuel to each of said burner segments in asuccessive predetermined pattern solely upon the filling of said burnersegments by said filling means,

said sequential control means including a servo actuated piston having afluid reaction chamber, means for admitting servo fluid into saidchamber for imparting rectilinear movement thereto, an elongated hollowmember extending axially in a cavity from the side of said pistonopposite said chamber and carried thereby, the end of said elongatedhollow member sealing fuel fed into said cavity from egressing into thehollow portion of said elongated member when in the operative condition,a plurality of ports communicating with said burner segments foradmitting metered fuel therein, a tubular member having an annularpassageway formed therein concentrically mounted about said elongatedhollow member, means for admitting fill fuel therein through a radialopening formed in said tubular member so as to flow fill fuel throughthe annular passageway through the radial opening to one of said ports,and said radial opening being in spaced relationship to said end of theelongated hollow member so that said opening registers with said portsprior to permitting metered fuel in said cavity to egress into saidports.

2. A fuel control as claimed in claim 1 including servo control meanshaving a pilot valve for regulating the flow of servo fluid into and outof said fluid reaction chamber, and sensor means including means forconnecting said fluid reaction chamber to said pilot valve for measuringthe condition in dicative of the presence of fuel in said burner segmentfor positioning said pilot valve 3. A fuel control as claimed in claim 2including feedback means interconnecting said servo actuated piston andsaid pilot valve.

4. A fuel control as claimed in claim 2 wherein said feedback means andsaid connecting means include a lever having one end pivotally connectedto said servo piston, the other end pivotally connected to said pilotvalve and said sensor being pivotally connected therebetween.

5. A fuel control as claimed in claim 4 wherein said sensor meansincludes a casing, a plurality of piston segments each having a separatefluid receiving chamber, and pressure taps communicating each of saidburner segments with each of said fluid receiving chambers forpositioning said piston segments upon reaching a predetermined value.

